Communication control system and control method thereof

ABSTRACT

In a communication control system for controlling packet transfer conducted by a plurality of logical channels between nodes, a circuit is provided for recording, in a descriptor for recording information regarding transfer by each logical channel, information including a stop bit, an activation bit, the number of logical channel to be activated, an identification value, the number of logical channel to be monitored and a monitoring identification value which are information regarding the order of transfer by each logical channel, and a data link layer includes a circuit for executing transfer by each logical channel based on the order of transfer by each logical channel designated by a descriptor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a communication control system forcontrolling packet transfer conducted by a plurality of logical channelsand, more particularly, to a communication control system for conductingsequential processing and synchronous processing of transmission data ata high speed.

2. Description of the Related Art

In a communication control device for providing communication betweennodes connected by a virtual channel protocol, at the time of conductingmessage transfer and data transfer between nodes by using packets, alogical channel is set up between the nodes by a management layer incharge of transfer control and, a descriptor which records informationfor transmission and reception is prepared for each packet transfer toactivate a transmission and reception control circuit.

Although the descriptor is analyzed by a data link layer of thecommunication control device, packet transfer is conducted independentlyfor each logical channel in a conventional device, so that logicalchannels are independent of each other.

Therefore, in a case where sequential or synchronous transfer processingis required between a plurality of logical channels, a management layerrealized by higher-order software etc. monitors the end of packettransfer by such a waiting system as polling or interruption and afterreceiving a notification of the end of transfer, causes other logicalchannel to activate transfer.

Here, description will be made of sequential processing and synchronousprocessing by a conventional communication control system.

FIG. 9 is a flow chart for use in explaining sequential processing by aconventional communication control system, with reference to whichdescription will be made with respect to sequential processing ofsequentially transferring two packets, a first packet and a secondpacket as an example.

With reference to FIG. 9, in the sequential processing of transferringthe two packets, first, a higher-order management layer transfers adescriptor of the first packet to the communication control device, adata link layer transfers the first packet by a logical channel of thelogical channel number “1” (Step 901) and the management layer waits fortransfer confirmation by polling, interruption or the like to confirmthe transfer (Step 902). The management layer again transfers adescriptor of the second packet to the communication control device, thedata link layer transfers the second packet by a logical channel of thelogical channel number “2” (Step 903) and the management layer againwaits for transfer confirmation to confirm transfer (Step 904) to resultin normal end. When an error occurs at each of the Steps 902 and 904,the routine proceeds to error processing.

As described in the foregoing, since in conventional sequentialprocessing, a higher-order management layer confirms transfer at everypacket transfer, a large overhead is generated such as consumption ofCPU resources by polling and a delay caused by notification of aninterruption and the subsequent confirmation thereof.

The numbers “1” and “2”, of the logical channels are here recited as anexample. The reason the different logical channels are used for thefirst packet and the second packet is that in a case, as the simplestexample, where the processing of continuously transferring packets byusing the logical channel number “1” is to be executed after the firstpacket without waiting for a result, if the second packet uses the samelogical channel number “1”, transfer of the second packet is keptwaiting until the result is obtained because of the policy of ascheduler.

FIG. 10 is a flow chart for use in explaining synchronous processing ofa plurality of packets by a plurality of logical channels by aconventional communication control system, with reference to whichdescription is made as an example with respect to synchronous processingof simultaneously transferring two packets, a second packet and a thirdpacket after the transfer of a first packet is completed.

With reference to FIG. 10, in the synchronous processing of the twopackets, first, a higher-order management layer transfers a descriptorof the first packet to a communication control device, a data link layertransfers the first packet by a logical channel of the logical channelnumber “1” (Step 1001) and the management layer waits for transferconfirmation by polling, interruption or the like to confirm thetransfer (Step 1001). Subsequently, the management layer transfersdescriptors of the second packet and the third packet to thecommunication control device, the data link layer transfers the secondpacket by the logical channel number “2” (Step 1003) and then the thirdpacket by the logical channel number “3” (Step 1004) and the managementlayer waits for confirmation of transfer of the two packets to confirmthe transfer (Step 1005) to result in normal end. When an error occursat each of the Steps 1002 and 1005, the routine proceeds to errorprocessing.

As described in the foregoing, also in conventional synchronousprocessing, transfer is confirmed by a higher-order management layer atevery packet transfer and a time lag is generated in transferring adescriptor to the communication device (Steps 1002 to 1003) to cause alarge overhead.

In recent years, in the field of communication means for conductingpacket communication, there appear a communication device and acommunication means employing such an extremely high speed medium asoptical communication using an optical cable including GigaBit Ether.

However, communication control systems operating these communicationdevices fail to fully make use of a capacity of high-speed media.

Main reason is overhead between a management layer realized by softwareand a data link layer realized by a communication device.

In a computer network, between a communication application as softwareand a communication device as hardware, there exist numerous softwarestacks, and overhead therebetween hinders improvement in communicationperformance.

Generation of the overhead is caused because as illustrated in theabove-described examples of the sequential control and synchronouscontrol in FIGS. 9 and 10, even in a case of transmitting each packetaccording to predetermined rules, a higher-order management layertransfers a descriptor to a communication device every time each packetis to be transferred and after the transmission, confirms the transfer.

Demanded is a system in which a data link layer takes charge of suchprocessing as sequential transmission of each packet and a higher-ordermanagement layer transfers data to be transmitted together withinformation including the order of the transmission thereof to acommunication device in the lump.

One of conventional techniques of making a data link layer executeprocessing which is ordinarily conducted by a higher-order managementlayer is the art disclosed in Japanese Patent Laying-Open (Kokai) No.Heisei 9-204376. According to the technique, information about adestination of transfer data which a higher-order management layertransfers to a communication device is described in a form unique to asystem and converted into an ordinary address on a network by a datalink layer. The conventional technique, however, is intended not toreduction in overhead between a data link layer and a management layerbut to distributional processing of communication address management andfails to cope with high-speed sequential processing and synchronousprocessing of transmission data. Moreover, for making the data linklayer to execute complicated processing of address management,complicated device structure is required.

SUMMARY OF THE INVENTION

An object of the present invention is to eliminate the above-describedshortcomings of conventional techniques and to provide a communicationprocessing system which enables processing of sequential control,synchronous control, etc. conventionally requiring intervention ofprocessing by a higher-order management layer to be executed at a highspeed by a data link layer and also realizes the high-speed processingwithout requiring the data link layer to have complicated functions andprocessing.

According to the first aspect of the invention, a communication controlsystem having a data link layer which executes data transfer on alogical channel for controlling packet transfer conducted by a pluralityof the logical channels, comprises

-   -   means for recording, in a descriptor for recording information        regarding transfer by each logical channel, information        including information regarding the order of transfer by each        the logical channel, wherein    -   the data link layer includes    -   means for executing transfer by each the logical channel based        on the order of transfer by each the logical channel designated        by the descriptor.

In the preferred construction, the descriptor has

-   -   a stop bit indicating that transfer by the logical channel in        question is not to be executed immediately but to be started on        condition that transfer by other logical channel designated is        completed, and    -   the data link layer includes    -   means for temporarily stopping transfer processing by the        logical channel having the stop bit recorded in the descriptor        to wait for the transfer starting condition to be fulfilled.

In another preferred construction, the descriptor has

-   -   an activation bit indicating that completion of transfer by the        logical channel in question is set to be a transfer starting        condition for other logical channel designated, and    -   the data link layer includes    -   means for monitoring the completion of transfer by the logical        channel having the activation bit recorded in the descriptor to        determine fulfillment of the transfer starting condition for the        other logical channel designated upon the completion of the        transfer.

In another preferred construction, the descriptor has

-   -   a number of logical channel to be activated for specifying other        designated logical channel having the completion of transfer by        the logical channel in question set to be a transfer starting        condition, and    -   the data link layer includes    -   means for monitoring the completion of transfer by the logical        channel having the number of logical channel to be activated        recorded in the descriptor to determine fulfillment of the        transfer starting condition for a logical channel indicated by        the number of logical channel to be activated upon the        completion of the transfer of the logical channel.

In another preferred construction, the descriptor has

-   -   an activation bit indicating that completion of transfer by the        logical channel in question is set to be a transfer starting        condition for other logical channel designated,    -   a stop bit indicating that transfer by the logical channel in        question is not to be executed immediately but to be started on        condition that transfer by other logical channel designated is        completed, and    -   a number of logical channel to be activated for specifying other        designated logical channel having the completion of transfer by        the logical channel in question set to be a transfer starting        condition, and    -   the data link layer includes    -   means for temporarily stopping transfer processing by the        logical channel having the stop bit recorded in the descriptor        to wait for the transfer starting condition to be fulfilled,    -   means for monitoring the completion of transfer by the logical        channel having the activation bit recorded in the descriptor to        determine fulfillment of the transfer starting condition for the        other logical channel designated upon the completion of the        transfer, and    -   means for monitoring the completion of transfer by the logical        channel having the number of logical channel to be activated        recorded in the descriptor to determine fulfillment of the        transfer starting condition for a logical channel indicated by        the number of logical channel to be activated upon the        completion of the transfer of the logical channel.

In another preferred construction, the descriptor has

-   -   a number of logical channel to be monitored for, in order to        monitor the completion of transfer by other designated logical        channel which is set to be a transfer starting condition for the        logical channel in question, specifying the designated other        logical channel to be monitored, and    -   the data link layer includes    -   means for temporarily stopping transfer by the logical channel        having the number of logical channel to be monitored recorded in        the descriptor and monitoring the completion of transfer by a        logical channel indicated by the number of logical channel to be        monitored to determine fulfillment of the transfer starting        condition for the logical channel in question upon the        completion of the transfer.

In another preferred construction, the descriptor has

-   -   an activation bit indicating that completion of transfer by the        logical channel in question is set to be a transfer starting        condition for other logical channel designated,    -   a number of logical channel to be activated for specifying other        designated logical channel having the completion of transfer by        the logical channel in question set to be a transfer starting        condition, and    -   a number of logical channel to be monitored for, in order to        monitor the completion of transfer by other designated logical        channel which is set to be a transfer starting condition for the        logical channel in question, specifying the designated other        logical channel to be monitored, and    -   the data link layer includes    -   means for monitoring the completion of transfer by the logical        channel having the activation bit recorded in the descriptor to        determine fulfillment of the transfer starting condition for the        other logical channel designated upon the completion of the        transfer,    -   means for monitoring the completion of transfer by the logical        channel having the number of logical channel to be activated        recorded in the descriptor to determine fulfillment of the        transfer starting condition for a logical channel indicated by        the number of logical channel to be activated upon the        completion of the transfer of the logical channel, and    -   means for temporarily stopping transfer by the logical channel        having the number of logical channel to be monitored recorded in        the descriptor and monitoring the completion of transfer by a        logical channel indicated by the number of logical channel to be        monitored to determine fulfillment of the transfer starting        condition for the logical channel in question upon the        completion of the transfer.

In another preferred construction, the descriptor has

-   -   an activation bit indicating that completion of transfer by the        logical channel in question is set to be a transfer starting        condition for other logical channel designated,    -   a stop bit indicating that transfer by the logical channel in        question is not to be executed immediately but to be started on        condition that transfer by other logical channel designated is        completed,    -   a number of logical channel to be activated for specifying other        designated logical channel having the completion of transfer by        the logical channel in question set to be a transfer starting        condition, and    -   a number of logical channel to be monitored for, in order to        monitor the completion of transfer by other designated logical        channel which is set to be a transfer starting condition for the        logical channel in question, specifying the designated other        logical channel to be monitored, and    -   the data link layer includes    -   means for temporarily stopping transfer processing by the        logical channel having the stop bit recorded in the descriptor        to wait for the transfer starting condition to be fulfilled,    -   means for monitoring the completion of transfer by the logical        channel having the activation bit recorded in the descriptor to        determine fulfillment of the transfer starting condition for the        other logical channel designated upon the completion of the        transfer,    -   means for monitoring the completion of transfer by the logical        channel having the number of logical channel to be activated        recorded in the descriptor to determine fulfillment of the        transfer starting condition for a logical channel indicated by        the number of logical channel to be activated upon the        completion of the transfer of the logical channel, and    -   means for temporarily stopping transfer by the logical channel        having the number of logical channel to be monitored recorded in        the descriptor and monitoring the completion of transfer by a        logical channel indicated by the number of logical channel to be        monitored to determine fulfillment of the transfer starting        condition for the logical channel in question upon the        completion of the transfer.

In another preferred construction, the descriptor has

-   -   an identification value and a monitoring identification value as        numerical data, and    -   the data link layer includes    -   means for comparing, at the time of determination of the        transfer starting condition, a value of the monitoring        identification value of the descriptor of a waiting logical        channel which is a logical channel on the side waiting for the        transfer starting condition to be fulfilled and a value of the        identification value of a preceding logical channel which is a        logical channel on the side which conducts transfer prior to the        waiting logical channel and whose transfer completion is the        transfer starting condition for the waiting logical channel to        determine fulfillment of the transfer starting condition only        when the value of the monitoring identification value and the        value of the identification value are equal.

In another preferred construction, the descriptor has

-   -   an activation bit indicating that completion of transfer by the        logical channel in question is set to be a transfer starting        condition for other logical channel designated,    -   a stop bit indicating that transfer by the logical channel in        question is not to be executed immediately but to be started on        condition that transfer by other logical channel designated is        completed,    -   a number of logical channel to be activated for specifying other        designated logical channel having the completion of transfer by        the logical channel in question set to be a transfer starting        condition, and    -   an identification value and a monitoring identification value as        numerical data, and    -   the data link layer includes    -   means for temporarily stopping transfer processing by the        logical channel having the stop bit recorded in the descriptor        to wait for the transfer starting condition to be fulfilled,    -   means for monitoring the completion of transfer by the logical        channel having the activation bit recorded in the descriptor to        determine fulfillment of the transfer starting condition for the        other logical channel designated upon the completion of the        transfer,    -   means for monitoring the completion of transfer by the logical        channel having the number of logical channel to be activated        recorded in the descriptor to determine fulfillment of the        transfer starting condition for a logical channel indicated by        the number of logical channel to be activated upon the        completion of the transfer of the logical channel, and    -   means for comparing, at the time of determination of the        transfer starting condition, a value of the monitoring        identification value of the descriptor of a waiting logical        channel which is a logical channel on the side waiting for the        transfer starting condition to be fulfilled and a value of the        identification value of a preceding logical channel which is a        logical channel on the side which conducts transfer prior to the        waiting logical channel and whose transfer completion is the        transfer starting condition for the waiting logical channel to        determine fulfillment of the transfer starting condition only        when the value of the monitoring identification value and the        value of the identification value are equal.

In another preferred construction, the descriptor has

-   -   a number of logical channel to be monitored for, in order to        monitor the completion of transfer by other designated logical        channel which is set to be a transfer starting condition for the        logical channel in question, specifying the designated other        logical channel to be monitored, and    -   an identification value and a monitoring identification value as        numerical data, and    -   the data link layer includes    -   means for temporarily stopping transfer by the logical channel        having the number of logical channel to be monitored recorded in        the descriptor and monitoring the completion of transfer by a        logical channel indicated by the number of logical channel to be        monitored to determine fulfillment of the transfer starting        condition for the logical channel in question upon the        completion of the transfer, and    -   means for comparing, at the time of determination of the        transfer starting condition, a value of the monitoring        identification value of the descriptor of a waiting logical        channel which is a logical channel on the side waiting for the        transfer starting condition to be fulfilled and a value of the        identification value of a preceding logical channel which is a        logical channel on the side which conducts transfer prior to the        waiting logical channel and whose transfer completion is the        transfer starting condition for the waiting logical channel to        determine fulfillment of the transfer starting condition only        when the value of the monitoring identification value and the        value of the identification value are equal.

According to the second aspect of the invention, a method of controllinga communication control system having a data link layer which executesdata transfer on a logical channel for controlling packet transferconducted by a plurality of the logical channels, comprising:

-   -   the step of recording, in a descriptor for recording information        regarding transfer by each logical channel, information        including information regarding the order of transfer by each        the logical channel, and    -   the step of the data link layer of executing transfer by each        the logical channel based on the order of transfer by each the        logical channel designated by the descriptor.

In the preferred construction, the method of controlling a communicationcontrol system further comprising

-   -   the step of recording in the descriptor a stop bit indicating        that transfer by the logical channel in question is not to be        executed immediately but to be started on condition that        transfer by other logical channel designated is completed, and    -   the step of the data link layer of temporarily stopping transfer        processing by the logical channel having the stop bit recorded        in the descriptor to wait for the transfer starting condition to        be fulfilled.

In another preferred construction, the method of controlling acommunication control system further comprising

-   -   the step of recording in the descriptor an activation bit        indicating that completion of transfer by the logical channel in        question is set to be a transfer starting condition for other        logical channel designated, and    -   the step of the data link layer of monitoring the completion of        transfer by the logical channel having the activation bit        recorded in the descriptor to determine fulfillment of the        transfer starting condition for the other logical channel        designated upon the completion of the transfer.

In another preferred construction, the method of controlling acommunication control system further comprising

-   -   the step of recording in the descriptor a number of logical        channel to be activated for specifying other designated logical        channel having the completion of transfer by the logical channel        in question set to be a transfer starting condition, and    -   the step of the data link layer of monitoring the completion of        transfer by the logical channel having the number of logical        channel to be activated recorded in the descriptor to determine        fulfillment of the transfer starting condition for a logical        channel indicated by the number of logical channel to be        activated upon the completion of the transfer of the logical        channel.

In another preferred construction, the method of controlling acommunication control system comprising

-   -   the step of recording in the descriptor a number of logical        channel to be monitored for, in order to monitor the completion        of transfer by other designated logical channel which is set to        be a transfer starting condition for the logical channel in        question, specifying the designated other logical channel to be        monitored, and    -   the step of the data link layer of temporarily stopping transfer        by the logical channel having the number of logical channel to        be monitored recorded in the descriptor and monitoring the        completion of transfer by a logical channel indicated by the        number of logical channel to be monitored to determine        fulfillment of the transfer starting condition for the logical        channel in question upon the completion of the transfer.

In another preferred construction, the method of controlling acommunication control system comprising

-   -   the step of recording in the descriptor an identification value        and a monitoring identification value as numerical data, and    -   the step of the data link layer of comparing, at the time of        determination of the transfer starting condition, a value of the        monitoring identification value of the descriptor of a waiting        logical channel which is a logical channel on the side waiting        for the transfer starting condition to be fulfilled and a value        of the identification value of a preceding logical channel which        is a logical channel on the side which conducts transfer prior        to the waiting logical channel and whose transfer completion is        the transfer starting condition for the waiting logical channel        to determine fulfillment of the transfer starting condition only        when the value of the monitoring identification value and the        value of the identification value are equal.

According to another aspect of the invention, a computer readable memorystoring a control program of a communication control system having adata link layer which executes data transfer on a logical channel forcontrolling packet transfer conducted by a plurality of the logicalchannels,

-   -   the control program comprising    -   the step of recording, in a descriptor for recording information        regarding transfer by each logical channel, information        including information regarding the order of transfer by each        the logical channel, and    -   the step of the data link layer of executing transfer by each        the logical channel based on the order of transfer by each the        logical channel designated by the descriptor.

Other objects, features and advantages of the present invention willbecome clear from the detailed description given herebelow.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given herebelow and from the accompanying drawings of thepreferred embodiment of the invention, which, however, should not betaken to be limitative to the invention, but are for explanation andunderstanding only.

In the drawings:

FIG. 1 is a block diagram showing a structure of a communication controlsystem according to a first embodiment of the present invention;

FIG. 2 is a diagram showing a format of a descriptor of the firstembodiment of the present invention;

FIG. 3 is a flow chart for use in explaining processing of communicationcontrol according to the first embodiment of the present invention;

FIG. 4 is a flow chart for use in explaining sequential processingconducted by the communication control system according to the firstembodiment of the present invention;

FIG. 5 is block diagram showing a structure of a communication controlsystem according to a second embodiment of the present invention;

FIG. 6 is a diagram showing a format of a descriptor according to thesecond embodiment of the present invention;

FIG. 7 is a flow chart for use in explaining processing of communicationcontrol according to the second embodiment of the present invention;

FIG. 8 is a flow chart for use in explaining synchronous processingconducted by the communication control system according to the secondembodiment of the present invention;

FIG. 9 is a flow chart for use in explaining sequential processingconducted by a conventional communication control system;

FIG. 10 is a flow chart for use in explaining synchronous processingconducted by a conventional communication control system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiment of the present invention will be discussedhereinafter in detail with reference to the accompanying drawings. Inthe following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be obvious, however, to those skilled in the art that the presentinvention may be practiced without these specific details. In otherinstance, well-known structures are not shown in detail in order tounnecessary obscure the present invention.

A communication control system, at the time of transferring a messageand data to a third party by using a plurality of logical channels, setsup a plurality of logical channels with a node of the third party andtransmits and receives the message and the data based on information ofa descriptor prepared by a management layer.

The descriptor includes a control segment in which control informationis described such as the number of a logical channel and a protocol foruse in communication and a data segment in which information isdescribed regarding data itself such as an address in a storage unitwhich stores a message to be transferred.

In the data transfer procedure, first, a management layer designates alogical channel to transfer a descriptor to a data link layer, the datalink layer subsequently analyzes the descriptor, sets up an appropriatepacket and outputs a message and data to a physical layer to executedata transfer to a node of a third party, and the management layerconfirms the transfer to complete the transfer.

In the communication control system of the present invention, withinformation including that regarding the transfer order of each logicalchannel recorded in a descriptor for recording information regardingtransfer of each logical channel which conducts each packet transfer, adata link layer executes transfer of each logical channel based on therecorded transfer order.

This arrangement enables sequential control and synchronous controlbetween logical channels to be conducted in the data link layer torealize high-speed and precise processing.

A communication control system according to the first embodiment of thepresent invention adopts a system in which recording, in a descriptor ofa logical channel of the side which first conducts transfer, the numberof a waiting logical channel of the side which starts transfer nextafter the data transfer is completed enables a data link layer toexecute sequential processing of data transfer based on the information.Hereinafter, the method is referred to as a passive system.

FIG. 1 is a block diagram showing a structure of a communication controlsystem according to a first embodiment of the present invention and FIG.2 is a diagram showing a format of a descriptor of the first embodimentof the present invention.

With reference to FIG. 2, the descriptor of the present embodimentincludes a control segment in which control information of data transferis described and a data segment in which information regarding data tobe transferred is described.

The control segment includes a number of logical channel to be used 51indicative of the number of a logical channel to be used for transfer, astop bit 52 indicating that transfer is temporarily stopped for thesynchronization with other logical channel, an activation bit 53indicating that the transition of other designated logical channel froma temporarily stopped state to an active state is made after thecompletion of the transfer to activate transfer, a number of logicalchannel to be activated 54 indicative of the number of a logical channelto be activated, and inherent control information 55 indicative ofcontrol information inherent to a protocol and a device for use incommunication control between nodes.

The data segment includes a data address 56 indicative of an address atwhich data information such as a length of data and data are stored.

With reference to FIG. 1, the communication control system of thepresent embodiment includes in a communication control device 100, aninter-node interface circuit 10, a plurality of logical channel first ton-th control devices 20, a scheduler/packet generation circuit 30, apacket reception processing unit 40, an input data buffer 50, an inputdata DMA (Direct Memory Access) engine 60, an output data buffer 70 andan output data DMA engine 80.

The inter-node interface 10, which provides the interface with a node ofa communication partner, is equivalent to a physical layer of thecommunication control device.

The logical channel control circuit 20 is connected when a logicalchannel is set up between nodes to operate according to a procedure ofcommunication between the nodes, that is, a communication protocol foruse between the nodes such as error control and flow control. Althoughthe system in the figure includes a number n of the first to the n-thlogical channel control circuits 20, the number can be any number aslong as the volume of hardware allows and when the circuit has afunction of controlling a plurality of logical channels, one circuit ispossible.

The input buffer 50 records each of the information 52 to 56 of thedescriptor shown in FIG. 2 for each number of logical channel to be used51. In other words, the descriptor format illustrated in FIG. 2 shows astructure of one entry to the input buffer 50.

The scheduler/packet generation unit 30 has a function of schedulingdescriptors basically in the order of their application to the inputbuffer 50 to activate the input data DMA engine 60 based on controlsegment information stored in the input buffer 50 and a data address 56of the data segment and generating a packet from the main body of datatransferred from a memory to ultimately allocate the packet to thelogical channel circuit 20 indicated by the number of logical channel tobe used 51.

In addition, when the stop bit 52 is set at the control segment, thepacket transfer is temporarily stopped and the unit 30 refrains fromgeneration of a packet and allocation of the same to the relevantlogical channel control circuit 20.

The packet reception processing unit 40 receives a data packet, atransmission confirmation notification packet or an error notificationpacket from a node of a partner and when confirming by the transmissionconfirmation notification packet that data transfer is normallyconducted, notifies a higher-order management layer of the completion ofthe packet processing, as well as checking a descriptor control segmentof a relevant logical channel in the input buffer 50 and when theactivation bit 53 is set, resetting the stop bit 52 of a logical channelindicated by the number of logical channel to be activated 54 to releasethe temporarily stopped state and put the logical channel to the activestate. When receiving the error notification packet, the unit 40 givesan error notification to the higher-order management layer throughinterruption etc.

Data transferred from the partner's node is multiplexed with an outputof the logical channel control circuit 20 and stored in the output databuffer 70 and then stored in the memory through the output DMA engine80. At this time, data packet reception is notified to the higher-ordermanagement layer through the packet reception processing unit 40 tonotify data arrival.

FIG. 3 is a flow chart for use in explaining processing of (passivesystem) communication control according to the first embodiment of thepresent invention.

With reference to FIG. 3, in the processing of the passive systemcommunication control according to the present embodiment, first, adescriptor is stored in the input data buffer 50 (Step 301) and thescheduler/packet generation unit 30 analyzes information of the storeddescriptor (Step 302).

Here, in a case where the stop bit 52 is recorded in the descriptor (thestop bit 52 is ON), temporarily stop transfer of a packet indicated bythe descriptor (Step 303) and wait for release of the temporary stop(Step 304) to execute transfer after the temporary stop is released(Steps 305 and 306).

On the other hand, in a case where the stop bit 52 is not recorded inthe descriptor (the stop bit 52 is OFF), start the transfer immediately(Steps 303 and 306).

In a case where the transfer succeeds, the activation bit 53 recorded inthe descriptor (the activation bit 53 is ON) represents that thereexists other logical channel being currently at the temporarily stoppedstate which is to be transferred after the present transfer iscompleted, and the number of logical channel to be activated 54indicates such a logical channel. In this case, therefore, release thetemporary stop of a logical channel indicated by the number of logicalchannel to be activated 54 to start the transfer (Steps 308 and 309) andend the transfer processing by the logical channel.

On the other hand, in a case of transfer success, if the activation bit53 is yet to be recorded in the descriptor (the activation bit 53 isOFF), end the transfer processing by the logical channel.

When data transfer at Step 307 fails, execute error processing and inthis case, even if the activation bit 53 is recorded, no release oftemporary stop of other logical channel is conducted.

Next, processing of the present embodiment will be described withrespect to a specific case as an example.

FIG. 4 is a flow chart for use in explaining sequential processing bythe communication control system according the first embodiment of thepresent invention, which shows an example of the simplest sequentialprocessing of transferring a second packet after a first packet istransferred and normal end thereof is confirmed.

With reference to FIG. 4, according to the passive system of the presentembodiment, after the first packet is transferred by the logical channelnumber “1” (Step 401), the second packet can be subsequently transferredby the logical channel number “2” without waiting for the result (Step402) to lead to normal end after waiting for only an ultimate result(Step 403).

The foregoing procedure enables more reduction of overhead for theconfirmation of transfer as compared with that by a conventionaltechnique. Although the simplest case is shown as an example here, themore the steps of the sequential processing are, the more effects theprocessing can achieve.

The passive system sequential processing in the example shown in FIG. 4will be described in more detail.

Assume in the following description that the first packet is transferredby a logical channel with the logical channel number “1” under thecontrol of the logical channel first control circuit and that thecorresponding descriptor is the descriptor A. Similarly, assume that thesecond packet is transferred by a logical channel with the logicalchannel number “2” under the control of the logical channel secondcontrol circuit and that the corresponding descriptor is the descriptorB.

First, with the activation bit 53 of the descriptor illustrated in FIG.2 set in order to activate the second packet after normal transfer iscompleted and with the number of logical channel to be activated 54 setto be “2” for use by the second packet, the descriptor A of the firstpacket is transferred to the communication control device.

Since the second packet is temporarily stopped until the end of transferof the first packet, with the stop bit 52 of the descriptor illustratedin FIG. 2 set, the descriptor B is transferred to the communicationcontrol device.

These descriptors A and B are stored in the input buffer 50.

Next, the scheduler/packet generation unit 30, in order to scheduledescriptors basically in the order of their application to the inputbuffer 50, first generates a packet based on the descriptor A andallocates the packet to the relevant logical channel first controlcircuit 20.

Since the descriptor B has the stop bit 52 of the control segment set,packet transfer is temporarily stopped and the unit 30 refrains fromgeneration of a packet and allocation thereof to a logical channelcontrol circuit.

Thereafter, when a notification of a transmission confirmation packetfor the first packet is made by the partner's node, the packet isnotified to the packet reception processing unit 40 through theinter-node interface 10 and the logical channel first control circuit20.

By checking a control segment of a descriptor having the logical channelnumber “1” corresponding to the first control circuit 20 in the inputbuffer, the packet reception processing unit 40 confirms the activationbit 53 being set and then recognizes data of the logical channel number“2” at the number of logical channel to be activated 54.

Furthermore, the packet reception processing unit 40 resets the stop bit52 of a control segment of a descriptor having the logical channelnumber “2”. As a result, temporary stop of the descriptor B fortransferring the second packet using the logical channel number “2” isreleased and a packet is generated by the scheduler/packet generationunit 30 and allocated to the logical channel second control circuit, sothat the second packet is transferred to the transfer destination node.In the preceding transfer of the first packet, when an errornotification packet is transferred from the partner's node, the packetreception processing unit 40 gives an error notification to thehigher-order management layer by interruption or the like.

As described in the foregoing, the communication control system of thepresent embodiment enables management of the order of transfer betweenlogical channels and the like to be conducted by a data link layerwithout intervention of a higher-order management layer, therebyexecuting processing such as packet sequential transfer at a high speedwithout useless processing.

In addition, the communication control system of the present embodimentrealizes the above-described effects not by burdening a data link layerwith processing of a higher-order management layer but by suchprocessing suitable for the data link layer as monitoring of transferend and reference to and updating of data of a descriptor.

Next, second embodiment of the present invention will be described.

A communication control system of the second embodiment of the presentinvention adopts a system in which in a descriptor of a logical channelof the side conducting transfer after temporary stop, the number of alogical channel of the side starting the preceding transfer whosetransfer completion is a condition of the release of the temporary stopis recorded and a data link layer executes sequential processing of datatransfer based on thus obtained information. Hereinafter, this system isreferred to as an active system.

FIG. 5 is a block diagram showing a structure of the communicationcontrol system according to the second embodiment of the presentinvention, while FIG. 6 is a diagram showing a format of a descriptoraccording to the second embodiment of the present invention.

With reference to FIG. 6, similarly to the first embodiment, thedescriptor of the present embodiment includes a control segment in whichcontrol information on data transfer is described and a data segment inwhich information regarding data to be transferred is described.

The difference from the first embodiment resides in that the activationbit 53 and the number of logical channel to be activated 54 are notrequired and a number of logical channel to be monitored 58 which is thenumber of a logical channel which conducts the preceding transfer andwhose normal end is to be monitored is provided, and the presentembodiment includes an identification value 57 as a unique value in alogical channel for identifying a descriptor and includes a monitoringidentification value 59 for similarly specifying a descriptor of otherlogical channel.

This is because data indicative of a correlation between a sideconducting the preceding transfer and a waiting side which is held in adescriptor of the waiting side is recorded by using the number oflogical channel to be monitored 58 and the side conducting the precedingtransfer executes none of the processing of the first embodiment for thewaiting side, so that there is no need of the activation bit 53 and thenumber of logical channel to be activated 54.

With respect to the identification value 57 and the monitoringidentification value 59, the identification value 57 is recorded in adescriptor of the side conducting the preceding transfer and themonitoring identification value 59 is recorded in a descriptor of thewaiting side and at the end of transfer by the side conducting thepreceding transfer, data of the identification value 57 and themonitoring identification value 59 are compared to each other to releasetemporary stop of the waiting side only when they are equal. Thisenables correspondence between the side conducting the precedingtransfer and the waiting side to be precisely determined.

An example of a structure of an active system communication controldevice 10 a according to the present embodiment shown in FIG. 5 is thesame as that of the passive system shown in FIG. 1, with the onlydifference being that the function of a packet reception processing unit40 a and the contents of a descriptor stored in an input buffer 50 a aremodified as described above with reference to FIG. 6. In the following,no description will be made of the same functions as those of thepassive system according to the first embodiment.

The input buffer 50 a records each of the information 52 to 59 of thedescriptor shown in FIG. 6 for each number of logical channel to be used51. In other words, the descriptor format illustrated in FIG. 6 shows astructure of one entry to the input buffer 50 a.

The scheduler/packet generation unit 30 has a function of schedulingdescriptors basically in the order of their application to the inputbuffer 50 a to activate the input data DMA engine 60 based on controlsegment information and a data address 56 of the data segment stored inthe input buffer 50 a and generating a packet from the main body of datatransferred from a memory to ultimately allocate the packet to thelogical channel circuit 20 indicated by the number of logical channel tobe used 51.

In addition, when the stop bit 52 is set at the control segment, thepacket transfer is temporarily stopped and the unit 30 refrains fromgeneration of a packet and allocation of the same to the relevantlogical channel control circuit 20.

The packet reception processing unit 40 a receives a data packet, atransmission confirmation notification packet or an error notificationpacket from a node of a partner and when confirming by the transmissionconfirmation notification packet that data transfer is normallyconducted, notifies a higher-order management layer of the completion ofthe packet processing, as well as searching all the descriptors storedin the input buffer 50 a for the number of logical channel to bemonitored 58 and the monitoring identification value 59 to find adescriptor whose values coincide with the number of logical channel tobe used 51 and the identification value 57 of the descriptor of thepacket whose transfer is completed. When there exists a coincidentdescriptor, reset the stop bit 52 of the control segment of the relevantdescriptor to release the temporarily stopped state and enter the activestate.

FIG. 7 is a flow chart for use in explaining processing of (activesystem) communication control according to the second embodiment of thepresent invention.

With reference to FIG. 7, in the processing of the active systemcommunication control according to the present embodiment, first, adescriptor is stored in the input data buffer 50 (Step 701) and thescheduler/packet generation unit 30 analyzes information of the storeddescriptor (Step 702).

Here, in a case where the stop bit 52 is recorded in the descriptor(Step 703), temporarily stop the transfer of a packet indicated by thedescriptor to monitor the end of transfer of a logical channeldesignated by the number of logical channel to be monitored 58 (Step704). Then, when the transfer of the logical channel to be monitored iscompleted (Step 705) and when the identification value 57 of thedescriptor of the logical channel to be monitored and the monitoringidentification value 59 of the descriptor of the waiting logical channelare equal (Step 706), release the temporary stop to execute transfer(Step 707). Here, even when the transfer of the logical channel to bemonitored is completed, if the identification value 57 and themonitoring identification value 59 are not equal to each other, theroutine again returns to Step 704 to monitor the completion of thetransfer of the same logical channel.

On the other hand, in a case where the stop bit 52 is not recorded inthe descriptor, start the transfer immediately (Steps 703 and 707).

Then, in a case where data transfer at Step 707 succeeds, if thetransfer processing by the logical channel is completed to result in afailure in transfer, execute the error processing.

Next, processing of the present embodiment will be described withrespect to a specific case as an example.

FIG. 8 is a flow chart for use in explaining synchronous processing bythe communication control system according the second embodiment of thepresent invention, which shows the simplest example of synchronousprocessing of simultaneously transferring a second packet and a thirdpacket after a first packet is transferred and normal end thereof isconfirmed. Assume that the second packet and the third packet need to betransferred as simultaneously as possible.

With reference to FIG. 8, according to the active system of the presentembodiment, after the first packet is transferred with the logicalchannel number “1” (Step 801), the second packet can be subsequentlytransferred with the logical channel number “2” (Step 802) andfurthermore the third packet can be transferred with the logical channelnumber “3” (Step 803) without waiting for the result to lead to normalend after waiting for only an ultimate result (Step 804).

The foregoing procedure enables more reduction of overhead for theconfirmation of transfer as compared with that by a conventionaltechnique, as well as improving synchronism between the second and thethird packets because of high-speed activation in the data link layer.

The active system synchronous processing in the example shown in FIG. 8will be described in more detail.

Assume in the following description that the first packet is transferredby a logical channel with the logical channel number “1” under thecontrol of the logical channel first control circuit and that thecorresponding descriptor is the descriptor A. Similarly, assume that thesecond packet is transferred by a logical channel with the logicalchannel number “2” under the control of the logical channel secondcontrol circuit and that the corresponding descriptor is the descriptorB, and that the third packet is transferred by a logical channel withthe logical channel number “2” under the control of the logical channelthird control circuit and that the corresponding descriptor is thedescriptor B.

First, in the active system, since the first packet is on the side to bemonitored, no special setting of a descriptor is necessary, so that thedescriptor is transferred to the communication control device with thenumber of logical channel to be used “1” set at the control segment ofthe descriptor and, for example, “5”, set at an arbitrary identificationvalue 57.

Since the second and the third packets are temporarily stopped to havetheir transfer activated after monitoring the end of normal transfer ofthe first packet, both of their descriptors are transferred to thecommunication control device, with the stop bit 52 set at the controlsegment, the number of logical channel to be monitored 58 set to “1”which is the number of logical channel to be used for the first packetand the monitoring identification value 59 set to “5” which is thedescriptor identification value of the first packet.

Since the scheduler/packet generation unit 30 schedules descriptorsbasically in the order of their storage into the input buffer 50, theunit first generates a packet based on the descriptor A and allocatesthe packet to the relevant logical channel first control circuit 20.

Since the descriptor has the stop bit 52 set at the control segment, thesecond packet is temporarily stopped and the unit 30 refrains fromgeneration of a packet and allocation thereof to a logical channelcontrol circuit. The third packet is similarly handled to enter thetemporarily stopped state.

Thereafter, upon notification of a transmission confirmation packet forthe first packet made by the partner's node, the packet is notified tothe packet reception processing unit 40 through the inter-node interface10 and the logical channel first control circuit 20.

The packet reception processing unit 40 searches all the descriptorsstored in the input buffer 50 for the number of logical channel to bemonitored 58 and the monitoring identification value 59 to find adescriptor whose values coincide with the logical channel number “1” andthe identification value “5” of the descriptor of the packet whosetransfer is completed. In this case, since descriptors of the secondpacket and the third packet are relevant, reset the stop bit 52 of thecontrol segments of both the descriptors.

As a result, the temporarily stopped state of the descriptors fortransferring the second and the third packets using the logical channelnumbers “2” and “3” is released, so that packets are generated by thescheduler/packet generation unit 30 and allocated to the logical channelsecond control circuit and the logical channel third control circuit,respectively, to simultaneously conduct transfer of the second and thethird packets to the transfer destination nodes.

When an error notification packet is transferred from the partner'snode, the packet reception processing unit 40 gives an errornotification to the higher-order management layer by interruption etc.

Thus, in addition to the same effects attained by the first embodiment,the communication control system according to the present embodimentenables such processing as synchronous transfer of packets to beaccurately executed at a high speed and with ease.

Moreover, strictly and precisely checking a correspondence of logicalchannels between the side conducting the preceding transfer and thewaiting side is enabled by the method employing collation of theidentification value 57.

As other embodiment, the above-described structures of the passivesystem according to the first embodiment and the active system accordingto the second embodiment can be freely combined.

More specifically, although the above-described communication control bya data link layer requires a descriptor to have at least one of thenumber of logical channel to be activated 54 and the number of logicalchannel to be monitored 58 which are data indicative of a correspondenceof logical channels between the side conducting the preceding transferand the waiting side, each processing using three information, thenumber of logical channel to be activated 54, the number of logicalchannel to be monitored 58 and the identification value 57, isindependent of each other to allow various combinations.

In addition, in a mode using the number of logical channel to beactivated 54, provision of the activation bit 53 can be omitted. This isbecause information whether a value is “set/not set” at the number oflogical channel to be activated 54 corresponds to information of“ON/OFF” of the activation bit 53.

Similarly, in a mode using the number of logical channel to be monitored58, provision of the stop bit 52 can be omitted. This is becauseinformation whether a value is “set/not set” at the number of logicalchannel to be monitored 58 corresponds to information of “ON/OFF” of thestop bit 52.

Nevertheless, the stop bit 52 and the activation bit 53 have theadvantage in that less resources are required for their provision andthey can be processed more easily than a system referring to theabove-described number of logical channel to be activated 54 and thenumber of logical channel to be monitored 58, and they can be used incombination with the system referring to the above-described number oflogical channel to be activated 54 and the number of logical channel tobe monitored 58 to make deliberate determination.

Furthermore, although in the active system synchronous processingaccording to the second embodiment, to one logical channel on the sideconducting the preceding transfer, the number of logical channel to bemonitored 58 of a plurality of logical channels on the waiting sidecorrespond, such a mode is possible as allows the same logical channelon the waiting side to correspond to the number of logical channel to beactivated 54 of a plurality of logical channels on the side conductingthe preceding transfer in the passive system of the first embodiment.

In this case, applicable to the transfer of a logical channel on theside conducting the preceding transfer corresponding to the same waitinglogical channel are such a method of releasing temporary stop when onetransfer of the plurality of logical channels is completed or a methodof releasing temporary stop when all the corresponding transfers arecompleted.

Each function of the communication control system according to thepresent embodiment can be realized not only by hardware but also byloading a computer program having each function (communication controlprogram) into a memory of a computer processing device. Thecommunication control program is stored in a recording medium (referencenumeral) such as a magnetic disc or a semiconductor memory. Then,loading the program from the recording medium into the computerprocessing device to control operation of the computer processing devicerealizes the above-described respective functions.

As described in the foregoing, the communication control system of thepresent invention attains the following effects.

First, overhead caused by intervention of a higher-order managementlayer at the time of communication processing can be reduced. The reasonis that transmission confirmation of transfer and the accompanyingactivation of subsequent packet transfer which are ordinarily conductedby a higher-order management layer are conducted in a data link layer.

The second effect is that a time lag and overhead caused by transferactivation by a higher-order management layer at the time of synchronoustransfer processing between a plurality of logical channels can bereduced. The reason is that synchronous transfer processing of aplurality of packets ordinarily conducted in a higher-order managementlayer upon normal end of certain packet transfer is realized by holdinga plurality of packets in a data link layer in advance to conductconfirmation of normal end and synchronous activation and transferprocessing of a plurality of packets in the data link layer.

Although the invention has been illustrated and described with respectto exemplary embodiment thereof, it should be understood by thoseskilled in the art that the foregoing and various other changes,omissions and additions may be made therein and thereto, withoutdeparting from the spirit and scope of the present invention. Therefore,the present invention should not be understood as limited to thespecific embodiment set out above but to include all possibleembodiments which can be embodies within a scope encompassed andequivalents thereof with respect to the feature set out in the appendedclaims.

1. A communication control system having a data link layer whichexecutes data transfer on a logical channel for controlling packettransfer conducted by a plurality of said logical channels betweennodes, comprising: means for recording, in a descriptor for recordinginformation regarding transfer by each logical channel, informationincluding information regarding an order of transfer by each saidlogical channel, wherein said data link layer includes means forexecuting data transfer by each said logical channel based on theinformation recorded in said descriptor including the informationregarding the order of transfer by each said logical channel designatedby said descriptor.
 2. The communication control system as set forth inclaim 1, wherein said descriptor has a stop bit indicating that transferby the logical channel in question is not to be executed immediately butto be started on condition that transfer by other logical channeldesignated is completed, and said data link layer includes means fortemporarily stopping transfer processing by said logical channel havingsaid stop bit recorded in said descriptor to wait for said transferstarting condition to be fulfilled.
 3. The communication control systemas set forth in claim 1, wherein said descriptor has an activation bitindicating that completion of transfer by the logical channel inquestion is set to be a transfer starting condition for other logicalchannel designated, and said data link layer includes means formonitoring the completion of transfer by said logical channel havingsaid activation bit recorded in said descriptor to determine fulfillmentof said transfer starting condition for said other logical channeldesignated upon the completion of the transfer.
 4. The communicationcontrol system as set forth in claim 1, wherein said descriptor has anactivation bit indicating that completion of transfer by the logicalchannel in question is set to be a transfer starting condition for otherlogical channel designated, and a stop bit indicating that transfer bythe logical channel in question is not to be executed immediately but tobe started on condition that transfer by other logical channeldesignated is completed, and said data link layer includes means fortemporarily stopping transfer processing by said logical channel havingsaid stop bit recorded in said descriptor to wait for said transferstarting condition to be fulfilled, and means for monitoring thecompletion of transfer by said logical channel having said activationbit recorded in said descriptor to determine fulfillment of saidtransfer starting condition for said other logical channel designatedupon the completion of the transfer.
 5. The communication control systemas set forth in claim 1, wherein said descriptor has a number of logicalchannel to be activated for specifying other designated logical channelhaving the completion of transfer by the logical channel in question setto be a transfer starting condition, and said data link layer includesmeans for monitoring the completion of transfer by said logical channelhaving said number of logical channel to be activated recorded in saiddescriptor to determine fulfillment of said transfer starting conditionfor a logical channel indicated by said number of logical channel to beactivated upon the completion of the transfer of said logical channel.6. The communication control system as set forth in claim 1, whereinsaid descriptor has a stop bit indicating that transfer by the logicalchannel in question is not to be executed immediately but to be startedon condition that transfer by other logical channel designated iscompleted, and a number of logical channel to be activated forspecifying other designated logical channel having the completion oftransfer by the logical channel in question set to be a transferstarting condition, and said data link layer includes means fortemporarily stopping transfer processing by said logical channel havingsaid stop bit recorded in said descriptor to wait for said transferstarting condition to be fulfilled, and means for monitoring thecompletion of transfer by said logical channel having said number oflogical channel to be activated recorded in said descriptor to determinefulfillment of said transfer starting condition for a logical channelindicated by said number of logical channel to be activated upon thecompletion of the transfer of said logical channel.
 7. The communicationcontrol system as set forth in claim 1, wherein said descriptor has anactivation bit indicating that completion of transfer by the logicalchannel in question is set to be a transfer starting condition for otherlogical channel designated, and a number of logical channel to beactivated for specifying other designated logical channel having thecompletion of transfer by the logical channel in question set to be atransfer starting condition, and said data link layer includes means formonitoring the completion of transfer by said logical channel havingsaid activation bit recorded in said descriptor to determine fulfillmentof said transfer starting condition for said other logical channeldesignated upon the completion of the transfer, and means for monitoringthe completion of transfer by said logical channel having said number oflogical channel to be activated recorded in said descriptor to determinefulfillment of said transfer starting condition for a logical channelindicated by said number of logical channel to be activated upon thecompletion of the transfer of said logical channel.
 8. The communicationcontrol system as set forth in claim 1, wherein said descriptor has anactivation bit indicating that completion of transfer by the logicalchannel in question is set to be a transfer starting condition for otherlogical channel designated, a stop bit indicating that transfer by thelogical channel in question is not to be executed immediately but to bestarted on condition that transfer by other logical channel designatedis completed, and a number of logical channel to be activated forspecifying other designated logical channel having the completion oftransfer by the logical channel in question set to be a transferstarting condition, and said data link layer includes means fortemporarily stopping transfer processing by said logical channel havingsaid stop bit recorded in said descriptor to wait for said transferstarting condition to be fulfilled, means for monitoring the completionof transfer by said logical channel having said activation bit recordedin said descriptor to determine fulfillment of said transfer startingcondition for said other logical channel designated upon the completionof the transfer, and means for monitoring the completion of transfer bysaid logical channel having said number of logical channel to beactivated recorded in said descriptor to determine fulfillment of saidtransfer starting condition for a logical channel indicated by saidnumber of logical channel to be activated upon the completion of thetransfer of said logical channel.
 9. The communication control system asset forth in claim 1, wherein said descriptor has a number of logicalchannel to be monitored for, in order to monitor the completion oftransfer by other designated logical channel which is set to be atransfer starting condition for the logical channel in question,specifying said designated other logical channel to be monitored, andsaid data link layer includes means for temporarily stopping transfer bysaid logical channel having said number of logical channel to bemonitored recorded in said descriptor and monitoring the completion oftransfer by a logical channel indicated by said number of logicalchannel to be monitored to determine fulfillment of said transferstarting condition for the logical channel in question upon thecompletion of the transfer.
 10. The communication control system as setforth in claim 1, wherein said descriptor has a stop bit indicating thattransfer by the logical channel in question is not to be executedimmediately but to be started on condition that transfer by otherlogical channel designated is completed, and a number of logical channelto be monitored for, in order to monitor the completion of transfer byother designated logical channel which is set to be a transfer startingcondition for the logical channel in question, specifying saiddesignated other logical channel to be monitored, and said data linklayer includes means for temporarily stopping transfer processing bysaid logical channel having said stop bit recorded in said descriptor towait for said transfer starting condition to be fulfilled, and means fortemporarily stopping transfer by said logical channel having said numberof logical channel to be monitored recorded in said descriptor andmonitoring the completion of transfer by a logical channel indicated bysaid number of logical channel to be monitored to determine fulfillmentof said transfer starting condition for the logical channel in questionupon the completion of the transfer.
 11. The communication controlsystem as set forth in claim 1, wherein said descriptor has anactivation bit indicating that completion of transfer by the logicalchannel in question is set to be a transfer starting condition for otherlogical channel designated, and a number of logical channel to bemonitored for, in order to monitor the completion of transfer by otherdesignated logical channel which is set to be a transfer startingcondition for the logical channel in question, specifying saiddesignated other logical channel to be monitored, and said data linklayer includes means for monitoring the completion of transfer by saidlogical channel having said activation bit recorded in said descriptorto determine fulfillment of said transfer starting condition for saidother logical channel designated upon the completion of the transfer,and means for temporarily stopping transfer by said logical channelhaving said number of logical channel to be monitored recorded in saiddescriptor and monitoring the completion of transfer by a logicalchannel indicated by said number of logical channel to be monitored todetermine fulfillment of said transfer starting condition for thelogical channel in question upon the completion of the transfer.
 12. Thecommunication control system as set forth in claim 1, wherein saiddescriptor has an activation bit indicating that completion of transferby the logical channel in question is set to be a transfer startingcondition for other logical channel designated, a stop bit indicatingthat transfer by the logical channel in question is not to be executedimmediately but to be started on condition that transfer by otherlogical channel designated is completed, and a number of logical channelto be monitored for, in order to monitor the completion of transfer byother designated logical channel which is set to be a transfer startingcondition for the logical channel in question, specifying saiddesignated other logical channel to be monitored, and said data linklayer includes means for temporarily stopping transfer processing bysaid logical channel having said stop bit recorded in said descriptor towait for said transfer starting condition to be fulfilled, means formonitoring the completion of transfer by said logical channel havingsaid activation bit recorded in said descriptor to determine fulfillmentof said transfer starting condition for said other logical channeldesignated upon the completion of the transfer, and means fortemporarily stopping transfer by said logical channel having said numberof logical channel to be monitored recorded in said descriptor andmonitoring the completion of transfer by a logical channel indicated bysaid number of logical channel to be monitored to determine fulfillmentof said transfer starting condition for the logical channel in questionupon the completion of the transfer.
 13. The communication controlsystem as set forth in claim 1, wherein said descriptor has a number oflogical channel to be activated for specifying other designated logicalchannel having the completion of transfer by the logical channel inquestion set to be a transfer starting condition, and a number oflogical channel to be monitored for, in order to monitor the completionof transfer by other designated logical channel which is set to be atransfer starting condition for the logical channel in question,specifying said designated other logical channel to be monitored, andsaid data link layer includes means for monitoring the completion oftransfer by said logical channel having said number of logical channelto be activated recorded in said descriptor to determine fulfillment ofsaid transfer starting condition for a logical channel indicated by saidnumber of logical channel to be activated upon the completion of thetransfer of said logical channel, and means for temporarily stoppingtransfer by said logical channel having said number of logical channelto be monitored recorded in said descriptor and monitoring thecompletion of transfer by a logical channel indicated by said number oflogical channel to be monitored to determine fulfillment of saidtransfer starting condition for the logical channel in question upon thecompletion of the transfer.
 14. The communication control system as setforth in claim 1, wherein said descriptor has a stop bit indicating thattransfer by the logical channel in question is not to be executedimmediately but to be started on condition that transfer by otherlogical channel designated is completed, a number of logical channel tobe activated for specifying other designated logical channel having thecompletion of transfer by the logical channel in question set to be atransfer starting condition, and a number of logical channel to bemonitored for, in order to monitor the completion of transfer by otherdesignated logical channel which is set to be a transfer startingcondition for the logical channel in question, specifying saiddesignated other logical channel to be monitored, and said data linklayer includes means for temporarily stopping transfer processing bysaid logical channel having said stop bit recorded in said descriptor towait for said transfer starting condition to be fulfilled, means formonitoring the completion of transfer by said logical channel havingsaid number of logical channel to be activated recorded in saiddescriptor to determine fulfillment of said transfer starting conditionfor a logical channel indicated by said number of logical channel to beactivated upon the completion of the transfer of said logical channel,and means for temporarily stopping transfer by said logical channelhaving said number of logical channel to be monitored recorded in saiddescriptor and monitoring the completion of transfer by a logicalchannel indicated by said number of logical channel to be monitored todetermine fulfillment of said transfer starting condition for thelogical channel in question upon the completion of the transfer.
 15. Thecommunication control system as set forth in claim 1, wherein saiddescriptor has an activation bit indicating that completion of transferby the logical channel in question is set to be a transfer startingcondition for other logical channel designated, a number of logicalchannel to be activated for specifying other designated logical channelhaving the completion of transfer by the logical channel in question setto be a transfer starting condition, and a number of logical channel tobe monitored for, in order to monitor the completion of transfer byother designated logical channel which is set to be a transfer startingcondition for the logical channel in question, specifying saiddesignated other logical channel to be monitored, and said data linklayer includes means for monitoring the completion of transfer by saidlogical channel having said activation bit recorded in said descriptorto determine fulfillment of said transfer starting condition for saidother logical channel designated upon the completion of the transfer,means for monitoring the completion of transfer by said logical channelhaving said number of logical channel to be activated recorded in saiddescriptor to determine fulfillment of said transfer starting conditionfor a logical channel indicated by said number of logical channel to beactivated upon the completion of the transfer of said logical channel,and means for temporarily stopping transfer by said logical channelhaving said number of logical channel to be monitored recorded in saiddescriptor and monitoring the completion of transfer by a logicalchannel indicated by said number of logical channel to be monitored todetermine fulfillment of said transfer starting condition for thelogical channel in question upon the completion of the transfer.
 16. Thecommunication control system as set forth in claim 1, wherein saiddescriptor has an activation bit indicating that completion of transferby the logical channel in question is set to be a transfer startingcondition for other logical channel designated, a stop bit indicatingthat transfer by the logical channel in question is not to be executedimmediately but to be started on condition that transfer by otherlogical channel designated is completed, a number of logical channel tobe activated for specifying other designated logical channel having thecompletion of transfer by the logical channel in question set to be atransfer starting condition, and a number of logical channel to bemonitored for, in order to monitor the completion of transfer by otherdesignated logical channel which is set to be a transfer startingcondition for the logical channel in question, specifying saiddesignated other logical channel to be monitored, and said data linklayer includes means for temporarily stopping transfer processing bysaid logical channel having said stop bit recorded in said descriptor towait for said transfer starting condition to be fulfilled, means formonitoring the completion of transfer by said logical channel havingsaid activation bit recorded in said descriptor to determine fulfillmentof said transfer starting condition for said other logical channeldesignated upon the completion of the transfer, means for monitoring thecompletion of transfer by said logical channel having said number oflogical channel to be activated recorded in said descriptor to determinefulfillment of said transfer starting condition for a logical channelindicated by said number of logical channel to be activated upon thecompletion of the transfer of said logical channel, and means fortemporarily stopping transfer by said logical channel having said numberof logical channel to be monitored recorded in said descriptor andmonitoring the completion of transfer by a logical channel indicated bysaid number of logical channel to be monitored to determine fulfillmentof said transfer starting condition for the logical channel in questionupon the completion of the transfer.
 17. The communication controlsystem as set forth in claim 1, wherein said descriptor has anidentification value and a monitoring identification value as numericaldata, and said data link layer includes means for comparing, at the timeof determination of said transfer starting condition, a value of saidmonitoring identification value of said descriptor of a waiting logicalchannel which is a logical channel on the side waiting for said transferstarting condition to be fulfilled and a value of said identificationvalue of a preceding logical channel which is a logical channel on theside which conducts transfer prior to said waiting logical channel andwhose transfer completion is said transfer starting condition for saidwaiting logical channel to determine fulfillment of said transferstarting condition only when the value of said monitoring identificationvalue and the value of said identification value are equal.
 18. Thecommunication control system as set forth in claim 1, wherein saiddescriptor has a stop bit indicating that transfer by the logicalchannel in question is not to be executed immediately but to be startedon condition that transfer by other logical channel designated iscompleted, and an identification value and a monitoring identificationvalue as numerical data, and said data link layer includes means fortemporarily stopping transfer processing by said logical channel havingsaid stop bit recorded in said descriptor to wait for said transferstarting condition to be fulfilled, and means for comparing, at the timeof determination of said transfer starting condition, a value of saidmonitoring identification value of said descriptor of a waiting logicalchannel which is a logical channel on the side waiting for said transferstarting condition to be fulfilled and a value of said identificationvalue of a preceding logical channel which is a logical channel on theside which conducts transfer prior to said waiting logical channel andwhose transfer completion is said transfer starting condition for saidwaiting logical channel to determine fulfillment of said transferstarting condition only when the value of said monitoring identificationvalue and the value of said identification value are equal.
 19. Thecommunication control system as set forth in claim 1, wherein saiddescriptor has an activation bit indicating that completion of transferby the logical channel in question is set to be a transfer startingcondition for other logical channel designated, and an identificationvalue and a monitoring identification value as numerical data, and saiddata link layer includes means for monitoring the completion of transferby said logical channel having said activation bit recorded in saiddescriptor to determine fulfillment of said transfer starting conditionfor said other logical channel designated upon the completion of thetransfer, and means for comparing, at the time of determination of saidtransfer starting condition, a value of said monitoring identificationvalue of said descriptor of a waiting logical channel which is a logicalchannel on the side waiting for said transfer starting condition to befulfilled and a value of said identification value of a precedinglogical channel which is a logical channel on the side which conductstransfer prior to said waiting logical channel and whose transfercompletion is said transfer starting condition for said waiting logicalchannel to determine fulfillment of said transfer starting conditiononly when the value of said monitoring identification value and thevalue of said identification value are equal.
 20. The communicationcontrol system as set forth in claim 1, wherein said descriptor has anactivation bit indicating that completion of transfer by the logicalchannel in question is set to be a transfer starting condition for otherlogical channel designated, a stop bit indicating that transfer by thelogical channel in question is not to be executed immediately but to bestarted on condition that transfer by other logical channel designatedis completed, and an identification value and a monitoringidentification value as numerical data, and said data link layerincludes means for temporarily stopping transfer processing by saidlogical channel having said stop bit recorded in said descriptor to waitfor said transfer starting condition to be fulfilled, means formonitoring the completion of transfer by said logical channel havingsaid activation bit recorded in said descriptor to determine fulfillmentof said transfer starting condition for said other logical channeldesignated upon the completion of the transfer, and means for comparing,at the time of determination of said transfer starting condition, avalue of said monitoring identification value of said descriptor of awaiting logical channel which is a logical channel on the side waitingfor said transfer starting condition to be fulfilled and a value of saididentification value of a preceding logical channel which is a logicalchannel on the side which conducts transfer prior to said waitinglogical channel and whose transfer completion is said transfer startingcondition for said waiting logical channel to determine fulfillment ofsaid transfer starting condition only when the value of said monitoringidentification value and the value of said identification value areequal.
 21. The communication control system as set forth in claim 1,wherein said descriptor has a number of logical channel to be activatedfor specifying other designated logical channel having the completion oftransfer by the logical channel in question set to be a transferstarting condition, and an identification value and a monitoringidentification value as numerical data, and said data link layerincludes means for monitoring the completion of transfer by said logicalchannel having said number of logical channel to be activated recordedin said descriptor to determine fulfillment of said transfer startingcondition for a logical channel indicated by said number of logicalchannel to be activated upon the completion of the transfer of saidlogical channel, and means for comparing, at the time of determinationof said transfer starting condition, a value of said monitoringidentification value of said descriptor of a waiting logical channelwhich is a logical channel on the side waiting for said transferstarting condition to be fulfilled and a value of said identificationvalue of a preceding logical channel which is a logical channel on theside which conducts transfer prior to said waiting logical channel andwhose transfer completion is said transfer starting condition for saidwaiting logical channel to determine fulfillment of said transferstarting condition only when the value of said monitoring identificationvalue and the value of said identification value are equal.
 22. Thecommunication control system as set forth in claim 1, wherein saiddescriptor has a stop bit indicating that transfer by the logicalchannel in question is not to be executed immediately but to be startedon condition that transfer by other logical channel designated iscompleted, a number of logical channel to be activated for specifyingother designated logical channel having the completion of transfer bythe logical channel in question set to be a transfer starting condition,and an identification value and a monitoring identification value asnumerical data, and said data link layer includes means for temporarilystopping transfer processing by said logical channel having said stopbit recorded in said descriptor to wait for said transfer startingcondition to be fulfilled, means for monitoring the completion oftransfer by said logical channel having said number of logical channelto be activated recorded in said descriptor to determine fulfillment ofsaid transfer starting condition for a logical channel indicated by saidnumber of logical channel to be activated upon the completion of thetransfer of said logical channel, and means for comparing, at the timeof determination of said transfer starting condition, a value of saidmonitoring identification value of said descriptor of a waiting logicalchannel which is a logical channel on the side waiting for said transferstarting condition to be fulfilled and a value of said identificationvalue of a preceding logical channel which is a logical channel on theside which conducts transfer prior to said waiting logical channel andwhose transfer completion is said transfer starting condition for saidwaiting logical channel to determine fulfillment of said transferstarting condition only when the value of said monitoring identificationvalue and the value of said identification value are equal.
 23. Thecommunication control system as set forth in claim 1, wherein saiddescriptor has an activation bit indicating that completion of transferby the logical channel in question is set to be a transfer startingcondition for other logical channel designated, a number of logicalchannel to be activated for specifying other designated logical channelhaving the completion of transfer by the logical channel in question setto be a transfer starting condition, and an identification value and amonitoring identification value as numerical data, and said data linklayer includes means for monitoring the completion of transfer by saidlogical channel having said activation bit recorded in said descriptorto determine fulfillment of said transfer starting condition for saidother logical channel designated upon the completion of the transfer,means for monitoring the completion of transfer by said logical channelhaving said number of logical channel to be activated recorded in saiddescriptor to determine fulfillment of said transfer starting conditionfor a logical channel indicated by said number of logical channel to beactivated upon the completion of the transfer of said logical channel,and means for comparing, at the time of determination of said transferstarting condition, a value of said monitoring identification value ofsaid descriptor of a waiting logical channel which is a logical channelon the side waiting for said transfer starting condition to be fulfilledand a value of said identification value of a preceding logical channelwhich is a logical channel on the side which conducts transfer prior tosaid waiting logical channel and whose transfer completion is saidtransfer starting condition for said waiting logical channel todetermine fulfillment of said transfer starting condition only when thevalue of said monitoring identification value and the value of saididentification value are equal.
 24. The communication control system asset forth in claim 1, wherein said descriptor has an activation bitindicating that completion of transfer by the logical channel inquestion is set to be a transfer starting condition for other logicalchannel designated, a stop bit indicating that transfer by the logicalchannel in question is not to be executed immediately but to be startedon condition that transfer by other logical channel designated iscompleted, a number of logical channel to be activated for specifyingother designated logical channel having the completion of transfer bythe logical channel in question set to be a transfer starting condition,and an identification value and a monitoring identification value asnumerical data, and said data link layer includes means for temporarilystopping transfer processing by said logical channel having said stopbit recorded in said descriptor to wait for said transfer startingcondition to be fulfilled, means for monitoring the completion oftransfer by said logical channel having said activation bit recorded insaid descriptor to determine fulfillment of said transfer startingcondition for said other logical channel designated upon the completionof the transfer, means for monitoring the completion of transfer by saidlogical channel having said number of logical channel to be activatedrecorded in said descriptor to determine fulfillment of said transferstarting condition for a logical channel indicated by said number oflogical channel to be activated upon the completion of the transfer ofsaid logical channel, and means for comparing, at the time ofdetermination of said transfer starting condition, a value of saidmonitoring identification value of said descriptor of a waiting logicalchannel which is a logical channel on the side waiting for said transferstarting condition to be fulfilled and a value of said identificationvalue of a preceding logical channel which is a logical channel on theside which conducts transfer prior to said waiting logical channel andwhose transfer completion is said transfer starting condition for saidwaiting logical channel to determine fulfillment of said transferstarting condition only when the value of said monitoring identificationvalue and the value of said identification value are equal.
 25. Thecommunication control system as set forth in claim 1, wherein saiddescriptor has a number of logical channel to be monitored for, in orderto monitor the completion of transfer by other designated logicalchannel which is set to be a transfer starting condition for the logicalchannel in question, specifying said designated other logical channel tobe monitored, and an identification value and a monitoringidentification value as numerical data, and said data link layerincludes means for temporarily stopping transfer by said logical channelhaving said number of logical channel to be monitored recorded in saiddescriptor and monitoring the completion of transfer by a logicalchannel indicated by said number of logical channel to be monitored todetermine fulfillment of said transfer starting condition for thelogical channel in question upon the completion of the transfer, andmeans for comparing, at the time of determination of said transferstarting condition, a value of said monitoring identification value ofsaid descriptor of a waiting logical channel which is a logical channelon the side waiting for said transfer starting condition to be fulfilledand a value of said identification value of a preceding logical channelwhich is a logical channel on the side which conducts transfer prior tosaid waiting logical channel and whose transfer completion is saidtransfer starting condition for said waiting logical channel todetermine fulfillment of said transfer starting condition only when thevalue of said monitoring identification value and the value of saididentification value are equal.
 26. The communication control system asset forth in claim 1, wherein data transfer is completed when amanagement layer confirms the data transfer.
 27. The communicationcontrol system as set forth in claim 1, wherein a management layerdesignates a logical channel to transfer said descriptor to the datalink layer, said data link layer analyzes said descriptor, sets up anappropriate packet and outputs a message and data to a physical layer toexecute data transfer to a node of a third party, and the managementlayer confirms the data transfer to complete the transfer.
 28. Thecommunication control system as set forth in claim 1, wherein theinformation recorded in said descriptor also includes a number of alogical channel used to transfer said descriptor from a management layerto said data link layer.
 29. A method of controlling a communicationcontrol system having a data link layer which executes data transfer ona logical channel for controlling packet transfer conducted by aplurality of said logical channels between nodes, comprising the stepsof: the step of recording, in a descriptor for recording informationregarding transfer by each logical channel, information includinginformation regarding an order of transfer by each said logical channel,and the step of said data link layer of executing data transfer by eachsaid logical channel based on the information recorded in saiddescriptor including the information regarding the order of transfer byeach said logical channel designated by said descriptor.
 30. The methodof controlling a communication control system as set forth in claim 29,further comprising: the step of recording in said descriptor a stop bitindicating that transfer by the logical channel in question is not to beexecuted immediately but to be started on condition that transfer byother logical channel designated is completed, and the step of said datalink layer of temporarily stopping transfer processing by said logicalchannel having said stop bit recorded in said descriptor to wait forsaid transfer starting condition to be fulfilled.
 31. The method ofcontrolling a communication control system as set forth in claim 29,further comprising: the step of recording in said descriptor anactivation bit indicating that completion of transfer by the logicalchannel in question is set to be a transfer starting condition for otherlogical channel designated, and the step of said data link layer ofmonitoring the completion of transfer by said logical channel havingsaid activation bit recorded in said descriptor to determine fulfillmentof said transfer starting condition for said other logical channeldesignated upon the completion of the transfer.
 32. The method ofcontrolling a communication control system as set forth in claim 29,further comprising: the step of recording in said descriptor a stop bitindicating that transfer by the logical channel in question is not to beexecuted immediately but to be started on condition that transfer byother logical channel designated is completed, the step of recording insaid descriptor an activation bit indicating that completion of transferby the logical channel in question is set to be a transfer startingcondition for other logical channel designated, and the steps of saiddata link layer of: temporarily stopping transfer processing by saidlogical channel having said stop bit recorded in said descriptor to waitfor said transfer starting condition to be fulfilled, and monitoring thecompletion of transfer by said logical channel having said activationbit recorded in said descriptor to determine fulfillment of saidtransfer starting condition for said other logical channel designatedupon the completion of the transfer.
 33. The method of controlling acommunication control system as set forth in claim 29, furthercomprising: the step of recording in said descriptor a number of logicalchannel to be activated for specifying other designated logical channelhaving the completion of transfer by the logical channel in question setto be a transfer starting condition, and the step of said data linklayer of monitoring the completion of transfer by said logical channelhaving said number of logical channel to be activated recorded in saiddescriptor to determine fulfillment of said transfer starting conditionfor a logical channel indicated by said number of logical channel to beactivated upon the completion of the transfer of said logical channel.34. The method of controlling a communication control system as setforth in claim 29, comprising: the step of recording in said descriptora stop bit indicating that transfer by the logical channel in questionis not to be executed immediately but to be started on condition thattransfer by other logical channel designated is completed, the step ofrecording in said descriptor a number of logical channel to be activatedfor specifying other designated logical channel having the completion oftransfer by the logical channel in question set to be a transferstarting condition, and the steps of said data link layer of:temporarily stopping transfer processing by said logical channel havingsaid stop bit recorded in said descriptor to wait for said transferstarting condition to be fulfilled, and monitoring the completion oftransfer by said logical channel having said number of logical channelto be activated recorded in said descriptor to determine fulfillment ofsaid transfer starting condition for a logical channel indicated by saidnumber of logical channel to be activated upon the completion of thetransfer of said logical channel.
 35. The method of controlling acommunication control system as set forth in claim 29, furthercomprising: the step of recording in said descriptor an activation bitindicating that completion of transfer by the logical channel inquestion is set to be a transfer starting condition for other logicalchannel designated, the step of recording in said descriptor a number oflogical channel to be activated for specifying other designated logicalchannel having the completion of transfer by the logical channel inquestion set to be a transfer starting condition, and the steps of saiddata link layer of: monitoring the completion of transfer by saidlogical channel having said activation bit recorded in said descriptorto determine fulfillment of said transfer starting condition for saidother logical channel designated upon the completion of the transfer,and monitoring the completion of transfer by said logical channel havingsaid number of logical channel to be activated recorded in saiddescriptor to determine fulfillment of said transfer starting conditionfor a logical channel indicated by said number of logical channel to beactivated upon the completion of the transfer of said logical channel.36. The method of controlling a communication control system as setforth in claim 29, comprising: the step of recording in said descriptora stop bit indicating that transfer by the logical channel in questionis not to be executed immediately but to be started on condition thattransfer by other logical channel designated is completed, the step ofrecording in said descriptor an activation bit indicating thatcompletion of transfer by the logical channel in question is set to be atransfer starting condition for other logical channel designated, thestep of recording in said descriptor a number of logical channel to beactivated for specifying other designated logical channel having thecompletion of transfer by the logical channel in question set to be atransfer starting condition, and the steps of said data link layer of:temporarily stopping transfer processing by said logical channel havingsaid stop bit recorded in said descriptor to wait for said transferstarting condition to be fulfilled, monitoring the completion oftransfer by said logical channel having said activation bit recorded insaid descriptor to determine fulfillment of said transfer startingcondition for said other logical channel designated upon the completionof the transfer, and monitoring the completion of transfer by saidlogical channel having said number of logical channel to be activatedrecorded in said descriptor to determine fulfillment of said transferstarting condition for a logical channel indicated by said number oflogical channel to be activated upon the completion of the transfer ofsaid logical channel.
 37. The method of controlling a communicationcontrol system as set forth in claim 29, comprising: the step ofrecording in said descriptor a number of logical channel to be monitoredfor, in order to monitor the completion of transfer by other designatedlogical channel which is set to be a transfer starting condition for thelogical channel in question, specifying said designated other logicalchannel to be monitored, and the step of said data link layer oftemporarily stopping transfer by said logical channel having said numberof logical channel to be monitored recorded in said descriptor andmonitoring the completion of transfer by a logical channel indicated bysaid number of logical channel to be monitored to determine fulfillmentof said transfer starting condition for the logical channel in questionupon the completion of the transfer.
 38. The method of controlling acommunication control system as set forth in claim 29, comprising: thestep of recording in said descriptor a stop bit indicating that transferby the logical channel in question is not to be executed immediately butto be started on condition that transfer by other logical channeldesignated is completed, the step of recording in said descriptor anumber of logical channel to be monitored for, in order to monitor thecompletion of transfer by other designated logical channel which is setto be a transfer starting condition for the logical channel in question,specifying said designated other logical channel to be monitored, andthe steps of said data link layer of: temporarily stopping transferprocessing by said logical channel having said stop bit recorded in saiddescriptor to wait for said transfer starting condition to be fulfilled,and temporarily stopping transfer by said logical channel having saidnumber of logical channel to be monitored recorded in said descriptorand monitoring the completion of transfer by a logical channel indicatedby said number of logical channel to be monitored to determinefulfillment of said transfer starting condition for the logical channelin question upon the completion of the transfer.
 39. The method ofcontrolling a communication control system as set forth in claim 29,comprising: the step of recording in said descriptor an activation bitindicating that completion of transfer by the logical channel inquestion is set to be a transfer starting condition for other logicalchannel designated, the step of recording in said descriptor a number oflogical channel to be monitored for, in order to monitor the completionof transfer by other designated logical channel which is set to be atransfer starting condition for the logical channel in question,specifying said designated other logical channel to be monitored, andthe steps of said data link layer of: monitoring the completion oftransfer by said logical channel having said activation bit recorded insaid descriptor to determine fulfillment of said transfer startingcondition for said other logical channel designated upon the completionof the transfer, and temporarily stopping transfer by said logicalchannel having said number of logical channel to be monitored recordedin said descriptor and monitoring the completion of transfer by alogical channel indicated by said number of logical channel to bemonitored to determine fulfillment of said transfer starting conditionfor the logical channel in question upon the completion of the transfer.40. The method of controlling a communication control system as setforth in claim 29, comprising: the step of recording in said descriptora stop bit indicating that transfer by the logical channel in questionis not to be executed immediately but to be started on condition thattransfer by other logical channel designated is completed, the step ofrecording in said descriptor an activation bit indicating thatcompletion of transfer by the logical channel in question is set to be atransfer starting condition for other logical channel designated, thestep of recording in said descriptor a number of logical channel to bemonitored for, in order to monitor the completion of transfer by otherdesignated logical channel which is set to be a transfer startingcondition for the logical channel in question, specifying saiddesignated other logical channel to be monitored, and the steps of saiddata link layer of: temporarily stopping transfer processing by saidlogical channel having said stop bit recorded in said descriptor to waitfor said transfer starting condition to be fulfilled, monitoring thecompletion of transfer by said logical channel having said activationbit recorded in said descriptor to determine fulfillment of saidtransfer starting condition for said other logical channel designatedupon the completion of the transfer, and temporarily stopping transferby said logical channel having said number of logical channel to bemonitored recorded in said descriptor and monitoring the completion oftransfer by a logical channel indicated by said number of logicalchannel to be monitored to determine fulfillment of said transferstarting condition for the logical channel in question upon thecompletion of the transfer.
 41. The method of controlling acommunication control system as set forth in claim 29, comprising: thestep of recording in said descriptor an identification value and amonitoring identification value as numerical data, and the step of saiddata link layer of comparing, at the time of determination of saidtransfer starting condition, a value of said monitoring identificationvalue of said descriptor of a waiting logical channel which is a logicalchannel on the side waiting for said transfer starting condition to befulfilled and a value of said identification value of a precedinglogical channel which is a logical channel on the side which conductstransfer prior to said waiting logical channel and whose transfercompletion is said transfer starting condition for said waiting logicalchannel to determine fulfillment of said transfer starting conditiononly when the value of said monitoring identification value and thevalue of said identification value are equal.
 42. The method ofcontrolling a communication control system as set forth in claim 29,comprising: the step of recording in said descriptor a stop bitindicating that transfer by the logical channel in question is not to beexecuted immediately but to be started on condition that transfer byother logical channel designated is completed, the step of recording insaid descriptor an identification value and a monitoring identificationvalue as numerical data, and the steps of said data link layer of:temporarily stopping transfer processing by said logical channel havingsaid stop bit recorded in said descriptor to wait for said transferstarting condition to be fulfilled, and comparing, at the time ofdetermination of said transfer starting condition, a value of saidmonitoring identification value of said descriptor of a waiting logicalchannel which is a logical channel on the side waiting for said transferstarting condition to be fulfilled and a value of said identificationvalue of a preceding logical channel which is a logical channel on theside which conducts transfer prior to said waiting logical channel andwhose transfer completion is said transfer starting condition for saidwaiting logical channel to determine fulfillment of said transferstarting condition only when the value of said monitoring identificationvalue and the value of said identification value are equal.
 43. Themethod of controlling a communication control system as set forth inclaim 29, comprising: the step of recording in said descriptor anactivation bit indicating that completion of transfer by the logicalchannel in question is set to be a transfer starting condition for otherlogical channel designated, the step of recording in said descriptor anidentification value and a monitoring identification value as numericaldata, and the steps of said data link layer of: monitoring thecompletion of transfer by said logical channel having said activationbit recorded in said descriptor to determine fulfillment of saidtransfer starting condition for said other logical channel designatedupon the completion of the transfer, and comparing, at the time ofdetermination of said transfer starting condition, a value of saidmonitoring identification value of said descriptor of a waiting logicalchannel which is a logical channel on the side waiting for said transferstarting condition to be fulfilled and a value of said identificationvalue of a preceding logical channel which is a logical channel on theside which conducts transfer prior to said waiting logical channel andwhose transfer completion is said transfer starting condition for saidwaiting logical channel to determine fulfillment of said transferstarting condition only when the value of said monitoring identificationvalue and the value of said identification value are equal.
 44. Themethod of controlling a communication control system as set forth inclaim 29, comprising: the step of recording in said descriptor a stopbit indicating that transfer by the logical channel in question is notto be executed immediately but to be started on condition that transferby other logical channel designated is completed, the step of recordingin said descriptor an activation bit indicating that completion oftransfer by the logical channel in question is set to be a transferstarting condition for other logical channel designated, the step ofrecording in said descriptor an identification value and a monitoringidentification value as numerical data, and the steps of said data linklayer of: temporarily stopping transfer processing by said logicalchannel having said stop bit recorded in said descriptor to wait forsaid transfer starting condition to be fulfilled, monitoring thecompletion of transfer by said logical channel having said activationbit recorded in said descriptor to determine fulfillment of saidtransfer starting condition for said other logical channel designatedupon the completion of the transfer, and comparing, at the time ofdetermination of said transfer starting condition, a value of saidmonitoring identification value of said descriptor of a waiting logicalchannel which is a logical channel on the side waiting for said transferstarting condition to be fulfilled and a value of said identificationvalue of a preceding logical channel which is a logical channel on theside which conducts transfer prior to said waiting logical channel andwhose transfer completion is said transfer starting condition for saidwaiting logical channel to determine fulfillment of said transferstarting condition only when the value of said monitoring identificationvalue and the value of said identification value are equal.
 45. Themethod of controlling a communication control system as set forth inclaim 29, wherein data transfer is completed when a management layerconfirms the data transfer.
 46. The method of controlling acommunication control system as set forth in claim 29, wherein amanagement layer designates a logical channel to transfer saiddescriptor to the data link layer, said data link layer analyzes saiddescriptor, sets up an appropriate packet and outputs a message and datato a physical layer to execute data transfer to a node of a third party,and the management layer confirms the data transfer to complete thetransfer.
 47. The method of controlling a communication control systemas set forth in claim 29, wherein the information recorded in saiddescriptor also includes a number of a logical channel used to transfersaid descriptor from a management layer to said data link layer.
 48. Acomputer readable memory storing a control program of a communicationcontrol system having a data link layer which executes data transfer ona logical channel for controlling packet transfer conducted by aplurality of said logical channels between nodes, said control programcomprising: the step of recording, in a descriptor for recordinginformation regarding transfer by each logical channel, informationincluding information regarding an order of transfer by each saidlogical channel, and the step of said data link layer of executing datatransfer by each said logical channel based on the information recordedin said descriptor including the information regarding the order oftransfer by each said logical channel designated by said descriptor. 49.The computer readable memory storing a control program of acommunication control system as set forth in claim 48, said controlprogram further comprising: the step of recording in said descriptor astop bit indicating that transfer by the logical channel in question isnot to be executed immediately but to be started on condition thattransfer by other logical channel designated is completed, and the stepof said data link layer of temporarily stopping transfer processing bysaid logical channel having said stop bit recorded in said descriptor towait for said transfer starting condition to be fulfilled.
 50. Thecomputer readable memory storing a control program of a communicationcontrol system as set forth in claim 48, said control program furthercomprising: the step of recording in said descriptor an activation bitindicating that completion of transfer by the logical channel inquestion is set to be a transfer starting condition for other logicalchannel designated, and the step of said data link layer of monitoringthe completion of transfer by said logical channel having saidactivation bit recorded in said descriptor to determine fulfillment ofsaid transfer starting condition for said other logical channeldesignated upon the completion of the transfer.
 51. The computerreadable memory storing a control program of a communication controlsystem as set forth in claim 48, said control program furthercomprising: the step of recording in said descriptor a number of logicalchannel to be activated for specifying other designated logical channelhaving the completion of transfer by the logical channel in question setto be a transfer starting condition, and the step of said data linklayer of monitoring the completion of transfer by said logical channelhaving said number of logical channel to be activated recorded in saiddescriptor to determine fulfillment of said transfer starting conditionfor a logical channel indicated by said number of logical channel to beactivated upon the completion of the transfer of said logical channel.52. The computer readable memory storing a control program of acommunication control system as set forth in claim 48, said controlprogram comprising: the step of recording in said descriptor a number oflogical channel to be monitored for, in order to monitor the completionof transfer by other designated logical channel which is set to be atransfer starting condition for the logical channel in question,specifying said designated other logical channel to be monitored, andthe step of said data link layer of temporarily stopping transfer bysaid logical channel having said number of logical channel to bemonitored recorded in said descriptor and monitoring the completion oftransfer by a logical channel indicated by said number of logicalchannel to be monitored to determine fulfillment of said transferstarting condition for the logical channel in question upon thecompletion of the transfer.
 53. The computer readable memory storing acontrol program of a communication control system as set forth in claim48, said control program comprising: the step of recording in saiddescriptor an identification value and a monitoring identification valueas numerical data, and the step of said data link layer of comparing, atthe time of determination of said transfer starting condition, a valueof said monitoring identification value of said descriptor of a waitinglogical channel which is a logical channel on the side waiting for saidtransfer starting condition to be fulfilled and a value of saididentification value of a preceding logical channel which is a logicalchannel on the side which conducts transfer prior to said waitinglogical channel and whose transfer completion is said transfer startingcondition for said waiting logical channel to determine fulfillment ofsaid transfer starting condition only when the value of said monitoringidentification value and the value of said identification value areequal.
 54. The computer readable memory storing a control program of acommunication control system as set forth in claim 48, wherein datatransfer is completed when a management layer confirms the datatransfer.
 55. The computer readable memory storing a control program ofa communication control system as set forth in claim 48, wherein amanagement layer designates a logical channel to transfer saiddescriptor to the data link layer, said data link layer analyzes saiddescriptor, sets up an appropriate packet and outputs a message and datato a physical layer to execute data transfer to a node of a third party,and the management layer confirms the data transfer to complete thetransfer.
 56. The computer readable memory storing a control program ofa communication control system as set forth in claim 48, wherein theinformation recorded in said descriptor also includes a number of alogical channel used to transfer said descriptor from a management layerto said data link layer.